sign s3

gistfile1.txt

const moment = require('moment')
const crypto = require('crypto')

exports.sign = (req, res) => {
  const s3Config = {
    bucket: 'assets.example.com',
    region: 's3-ap-southeast-1',
    keyStart: 'uploads/',
    params: {
      acl: 'public-read',
      AWSAccessKeyId: process.env.S3_ACCESSKEY_ID
    }
  }

  s3Config.params.policy = {
    expiration: moment()
      .add(1, 'days')
      .toISOString(),
    conditions: [
      { bucket: s3Config.bucket },
      { acl: s3Config.params.acl },
      { success_action_status: '201' },
      { 'x-requested-with': 'xhr' },
      ['starts-with', '$key', s3Config.keyStart],
      ['starts-with', '$Content-Type', '']
    ]
  }

  s3Config.params.policy = new Buffer(
    JSON.stringify(s3Config.params.policy)
  ).toString('base64')

  const hash = crypto.createHmac('sha1', process.env.S3_SECRET_KEY)

  s3Config.params.signature = new Buffer(
    hash.update(s3Config.params.policy).digest()
  ).toString('base64')

  res.json(s3Config)
}